using a laser pointer as a signaling device

n3wb said:

Greetings,

I am planning to build a laser pointer to be used as a signalling device. Ie in the woods/camping/etc

I do not own a laser currently and i have never built one either, hence my set of questions. The goal that i am trying to achieve is having a wide/thick enough beam to be visible from a far away distance. When the operator points the laser straight up to the sky, i need the beam to be wide enough so the observer (which is x miles away) to see it.

I emailed wicked lasers and asked about theier green kr\ypton laser ($1000) and they told me that the beam will be visible up to 50 meters away when pointed straight up (with no ex pander). Is this answer accurate? Seems like a very small distance.

My plan is to use a green laser (exact wavelength and power still undecided) with a x10 beam expander. I have been recommended 2 Sanwu Spiker 520nm 1W lasers and 2 Sanwu beam expanders. Here's a link: https://www.sanwulasers.com/product/spiker
and the expander: https://www.sanwulasers.com/product/x3beamexpander .

I am wondering how to approach this issue.
Should i use 1 really powerful laser?
or strap 2 less powerful together?
maybe even 4 lasers together? If i strap 4 lasers together do i need 4 separate beam expanders? is it possible to have 1 big beam expander?

again, the goal here is to use this as a signaling device out in the great outdoors, pointing up into the sky, not at each other .... so a few things to consider.... reliability, power consumption, duty cycle
budget - $0-1000 - for everything

any advice guys? thank you, n3wb

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Podo said:

IMO A powerful flashlight would do much better job if you want to signal people from far away (in the forest) . If the target is not looking towards the emitter source(laser beam), he/she will have a hard time noticing the beam light in the sky. So WL is right about that, even with a 1W 520nm krypton, the maximun effective range if one's looking from behind is around 50 to 100 meters only. (not to mention you want to point it straight into the sky).

After that the beam just diverges and getting wider and wider, weakening its brightness.

Still if you insist to pick a laser device, our challenger II 1W with the X3.3 Beam expander will suit all your needs on reliability, power consumption, duty cycle.

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n3wb said:

thank you for letting me know

What if I strap 4 of those together with expanders?
By how much increase in distance do you think that will do ?

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